During data replication, data from a primary cluster is copied to a backup or secondary cluster. The secondary cluster can be located at a geographically separated site from the primary cluster. This distance depends on the distance support that is available from your data replication product.

Overview of Sun StorageTek Availability Suite Data Replication

Sun StorageTek Availability Suite Lightweight Resource Groups

To a protection group, you can add a device group that is controlled by the Sun StorageTek Availability Suite software. The Sun Cluster Geographic Edition software creates a lightweight resource group for each device group. The name of a lightweight resource group has the following format:

AVSdevicegroupname-stor-rg

For example, a device group named avsdg that is controlled by the Sun StorageTek Availability Suite software has a lightweight resource group named avsdg-stor-rg.

The lightweight resource group collocates the logical host and the device group, a requirement of data replication with the Sun StorageTek Availability Suite remote mirror software.

Each lightweight resource group contains two resources:

A logical hostname resource for the local logical host that is used for replication of the device group. The name of this resource has the following format:

SSEdevicegroup-lh

An HAStoragePlus resource for controlling the collocation of the device group with the lightweight resource group. The name of this resource has the format AVSdevicegroupname-stor.

For more information about lightweight resource groups, see the Sun StorageTek Availability Suite documentation.

Sun StorageTek Availability Suite Replication Resource Groups

When a device group that is controlled by the Sun StorageTek Availability Suite software is added to a protection group, the Sun Cluster Geographic Edition software creates a special replication resource for that device group in the replication resource group. By monitoring these replication resource groups, the Sun Cluster Geographic Edition software
monitors the overall status of replication. One replication resource group with one replication resource is created for each protection group.

The name of the replication resource group has the following format:

AVSprotectiongroupname-rep-rg

The replication resource in the replication resource group monitors the replication status of the device group on the local cluster, which is reported by the Sun StorageTek Availability Suite remote mirror software.

The name of a replication resource has the following format:

AVSdevicegroupname-rep-rs

Initial Configuration of Sun StorageTek Availability Suite Software

This section describes the initial steps you must perform before you can configure Sun StorageTek Availability Suite replication in the Sun Cluster Geographic Edition product.

The example protection group, avspg, in this section has been configured on a partnership that consists of two clusters, cluster-paris and cluster-newyork. An application, which is encapsulated in the apprg1 resource
group, is protected by the avspg protection group. The application data is contained in the avsdg device group. The volumes in the avsdg device group can be Solaris Volume Manager volumes, VERITAS Volume Manager volumes, or raw device volumes.

The resource group, apprg1, and the device group, avsdg, are present on both the cluster-paris cluster and the cluster-newyork cluster. The avspg protection group protects the application data
by replicating data between the cluster-paris cluster and the cluster-newyork cluster.

Note –

Replication of each device group requires a logical host on the local cluster and a logical host on the partner cluster.

You cannot use the slash character (/) in a cluster tag in the Sun Cluster Geographic Edition software. If you are using raw DID devices, you cannot use predefined DID device group names such as dsk/s3.

Sun StorageTek Availability Suite Volume Sets

Before you can define a Sun StorageTek Availability Suite volume set, you must determine the following:

The data volumes to replicate such as vol-data-paris in avsdg on cluster-paris and vol-data-newyork in avsdg on cluster-newyork.

The bitmap volume that is needed for replication, such as vol-bitmap-paris in avsdg on cluster-paris and vol-bitmap-newyork in avsdg on cluster-newyork.

The logical host to use exclusively for replication of the device groupavsdg, such as the logical host logicalhost-paris-1 on cluster-paris and the logical host logicalhost-newyork-1 on cluster-newyork.

The volset file is located at /var/cluster/geo/avs/devicegroupname-volset.ini on all nodes of the primary and secondary clusters of the protection group. For example, the volset file for the device group avsdg is located at /var/cluster/geo/avs/avsdg-volset.ini.

The fields in the volume set file that are handled by the Sun Cluster Geographic Edition software are described in the following table. The Sun Cluster Geographic Edition software does not handle other parameters of the volume set, including disk queue, size of memory queue, and number of asynchronous threads. You must adjust
these parameters manually by using Sun StorageTek Availability Suite commands.

Field

Meaning

Description

phost

Primary host

The logical host of the server on which the primary volume resides.

pdev

Primary device

Primary volume partition. Specify full path names only.

pbitmap

Primary bitmap

Volume partition in which the bitmap of the primary partition is stored. Specify full path names only.

shost

Secondary host

The logical host of the server on which the secondary volume resides.

sdev

Secondary device

Secondary volume partition. Specify full path names only.

sbitmap

Secondary bitmap

Volume partition in which the bitmap of the secondary partition is stored. Specify full path names only.

ip

Network transfer protocol

IP address.

sync | async

Operating mode

sync is the mode in which the I/O operation is confirmed as complete only when the volume on the secondary cluster has been updated.

async is the mode in which the primary host I/O operation is confirmed as complete before updating the volumes on the secondary cluster.

giogroupname

I/O group name

An I/O group name. The set must be configured in the same I/O group on both the primary and the secondary cluster. This parameter is optional and need only be configured if you have an I/O group.

C

C tag

The device group name or resource tag of the local data and bitmap volumes in cases where this information is not implied by the name of the volume. For example, /dev/md/avsset/rdsk/vol indicates a device group named avsset. As another example, /dev/vx/rdsk/avsdg/vol indicates a device group named avsdg.

The Sun Cluster Geographic Edition software does not modify the value of the Sun StorageTek Availability Suite parameters. The software controls only the role of the volume set during switchover and takeover operations.

For more information about the format of the volume set files, refer to the Sun StorageTek Availability Suite documentation.

How to Set Up Raw-Disk Device Groups for Sun Cluster Geographic Edition Systems

Sun Cluster Geographic Edition supports the use of raw-disk device groups in addition to various volume managers. When you initially configure Sun Cluster, device groups are automatically configured for each raw device in the cluster. Use this procedure to reconfigure these automatically created device
groups for use with Sun Cluster Geographic Edition.

For the devices that you want to use, unconfigure the predefined device groups.

The following commands remove the predefined device groups for d7 and d8.

The volumes are encapsulated at the Sun Cluster device-group level. The Sun StorageTek Availability Suite software interacts with the Solaris Volume Manager disksets, or VERITAS Volume Manager disk group, or raw device through this device group interface. The path to the volumes depends on the volume type, as described in the following table.

Volume Type

Path

Solaris Volume Manager

/dev/md/disksetname/rdsk/d#, where # represents a number

VERITAS Volume Manager

/dev/vx/rdsk/diskgroupname/volumename

Raw device

/dev/did/rdsk/d#s#

Create a disk set, avsset, by using Solaris Volume Manager or a disk group, avsdg, by using VERITAS Volume Manager or a raw device on cluster-paris and cluster-newyork.

For example, if you configure the volume by using a raw
device, choose a raw device group, dsk/d3, on cluster-paris and cluster-newyork.

Create two volumes in the disk set or disk group on cluster-paris.

The Sun StorageTek Availability Suite software requires a dedicated bitmap volume for each data volume to track which modifications to the data volume when the system is in logging mode.

If you
use a raw device to configure the volumes, create two partitions, /dev/did/rdsk/d3s3 and /dev/did/rdsk/d3s4, on the /dev/did/rdsk/d3 device on cluster-paris.

Create two volumes in the disk set or disk group on cluster-newyork.

If you use a raw device to configure the volumes, create two partitions, /dev/did/rdsk/d3s5 and /dev/did/rdsk/d3s6, on the /dev/did/rdsk/d3 device
on cluster-paris.

Enabling a Sun StorageTek Availability Suite Volume Set

You can enable the Sun StorageTek Availability Suite volume sets in one of two ways:

Automatically, when the device group is added to the protection group, avspg

Use the automatic procedures to prepare the devicegroupname-volset.ini file when you are setting up Sun StorageTek Availability Suite software for the
first time. After you have prepared the file, when you add the device group to the protection group, set the Enable_volume_set property of a device group to True. The Sun StorageTek Availability Suite software reads the information in the devicegroupname-volset.ini file to automatically enable the device group.

Manually, after the device group is added to the protection group, avspg

Use the manual procedures to enable the volume sets when you are creating volumes on a system that has been configured.

Automatically Enabling a Solaris Volume Manager Volume Set

In this example, the cluster-paris cluster is the primary and avsset is a device group that contains a Solaris Volume Manager disk set.

The sample configuration file defines a volume set that replicates vol-data-paris from cluster-paris to vol-data-newyork on cluster-newyork. The volume set uses the bitmap volumes and logical hostnames that are specified
in the file.

Automatically Enabling a Raw Device Volume Set

In this example, the cluster-paris cluster is the primary and rawdg is the name of the device group that contains a raw device disk group, /dev/did/rdsk/d3.

Example 1–3 Automatically Enabling a Raw Device Volume Set

This example has the following entries in /var/cluster/geo/avs/avsdg-volset.ini file:

The sample configuration file defines a volume set that replicates d3s3 from cluster-paris to d3s5 on cluster-newyork. The volume set uses the bitmap volumes and logical hostnames that are specified in the file.

Manually Enabling Volume Sets

After you have added the device group to the protection group, avspg, you can manually enable the Sun StorageTek Availability Suite volume sets. Because the Sun Availability Suite commands are installed in different locations in the supported software versions, the following examples illustrate
how to enable volume sets for each software version.

How to Configure a Highly Available Cluster Global File System for Use With Sun StorageTek Availability Suite

Create the required file system on the volume set that you created in the previous step, vol-data-paris.

The application writes to this file system.

Add an entry to the /etc/vfstab file that contains information such as the mount location.

Note –

You must specify the mount at boot field in this file to no. This value prevents the file system from mounting on the secondary cluster at cluster startup. Instead, the Sun Cluster software and the Sun Cluster Geographic Edition framework handle mounting the file
system by using the HAStoragePlus resource when the application is brought online on the primary cluster. You must not mount data on the secondary cluster because data on the primary will not be replicated to the secondary cluster.

To handle the new file system, add the HAStoragePlus resource to the application resource group, apprg1.

Adding this resource ensures that the necessary file systems are remounted before the application is started.